It is mainly used for routine urine testing and leukocyte detection. Pyrrolate is an important substrate in the reagent strip module for determining urine leukocytes by drying method. Its determination principle is: that the neutrophil cytoplasm in leukocytes contains esterase. The esterase acts on the pyrrolyl ester in the test paper module, causing it to undergo a hydrolysis reaction and further couple with the diazonium salt to form a purple complex, the depth of which is proportional to the number of neutrophils.